1. Field of the Invention
The present invention is directed generally to making ice, and more particularly, to a method and apparatus for making clear ice within a fresh-food compartment of a refrigeration appliance, optionally to be dispensed through a door provided to restrict access into said fresh-food compartment.
2. Description of Related Art
Traditionally, making ice includes filling each individual ice mold in an ice tray with water and placing the ice tray in a freezer compartment having an ambient temperature well below 32° F. Once the water is fully frozen, the ice trays are removed from the freezer and each individual cube ejected from its mold into a bin or placed into a fluid medium to be cooled. However, such a batch process of making ice cubes requires manually filling the ice trays each time ice is to be made. Further, the extremely cold temperatures within the freezer compartment cause the ice to freeze more rapidly than air and other gasses trapped within the water can escape, causing the gas to be trapped within the ice, which leads to the ice having an opaque appearance.
More recently, automated ice makers have been disposed within the freezer compartments of refrigeration appliances where the ambient temperature is again much colder than the freezing point of water. The need for manually filling the ice trays is eliminated by the automatic distribution of water into each of the individual ice molds of the ice tray. But again, the rate at which the ice is frozen due to the ambient temperature within the freezer compartment is too fast to allow the gas within the water to escape before it freezes, which causes the ice to have an opaque appearance.
To minimize the opacity of the ice, more gradual methods of freezing water have been developed. Such methods require the cyclical submergence of a freezing finger into each individual ice mold of the ice tray within a freezer compartment in which the ambient temperature is well below the temperature at which water freezes. As the freezing fingers are submerged and removed from the water in the mold for each cube, air bubbles at the surface of each freezing finger follow the finger and float upward and out of the water. With the air bubbles removed, the resulting ice exhibits less opacity. But such methods chill the temperature of the fingers to a temperature much lower than the temperature at which water freezes to expedite freezing. It is typical for conventional freezing methods and devices to require chilling of the fingers to a temperature of −22° C., which corresponds to a temperature of −7.6° F. Such cold finger temperatures again freeze the water in contact with the fingers too quickly to allow the air bubbles to escape, resulting in an opaque region in the center of each cube. Additionally, the ice so created is stored within the freezer compartment with its ambient temperature much lower than the freezing temperature of water, resulting in the formation of an opaque ice film on the exterior surfaces of the ice.
Newer designs of refrigeration appliances have also recently moved the freezer compartment from its conventional location vertically above or laterally to the side of a fresh food compartment. Such conventional locations allowed the ice formed in the freezer compartment to fall under the force of gravity into a dispenser unit that could be accessed externally of the refrigeration appliance. This way, ice could be obtained without having to open the door to the freezer compartment. But with the freezer compartment vertically beneath the fresh food compartment, ice can not fall under the force of gravity into an ice dispenser provided at an accessible location in the door of the refrigeration unit. Moreover, some refrigeration units include only a fresh food compartment, giving consumers the option to utilize a separate large-capacity, stand-alone freezer unit located at a remote location away from the kitchen.
Accordingly, there is a need in the art for a method and apparatus for making substantially-transparent ice that minimizes opacity of the ice resulting from a trapped gas.